Anti-vaccination advocates rallied in Albany on Tuesday, calling on lawmakers for more support.

Those at the protest at the Capitol say potential legislation threatens their First Amendment right to decide what goes into their bodies and those of their children. Advocates also say their religious rights are under attack.

Mark Ustin, a health and human services policy expert, says three states have already eliminated exemptions entirely. Sixteen states allow both religious and philosophical objections. New York only allows a religious exemption and Ustin says eliminating the religious exemption is a delicate issue on both sides.

“The exemption is grounded in many ways — what our bedrock American principles of freedom of religion,” Ustin said. “But on the other hand, as we’ve seen recently, public health is a legitimate goal of the state and I think it’s very easy for people who have enjoyed the protection of mandatory vaccination for a long time to forget what some of these diseases are like.”

Ustin says school officials are tasked with deciding who gets a religious exemption. The criteria: It has to be “A sincerely held and genuine belief,” which is then tested by the school — but the testing varies.